BYT intermittently report the following dmesg error when executing piglit:
Unable to purge GPU memory due lock contention.
Subsequently, the machine fails other GPU test suites, and eventually hard-hangs.
I've performed hundreds of piglit runs on byt to reproduce this intermittent issue. The earliest I have seen it is:
029e8ff81c65c2e0562be4a5d93fe83a9df49233
radv: Initialize the shader_stats_dump flag.
It's likely that this is triggered by a i965 commit just prior to 029e8ff. I will continue to test in an attempt to identify the regression more precisely.